	US 12,221,669 B2
	Hot-rolled steel sheet, hot-dip coated steel sheet, and method for producing hot-rolled steel sheet
Kentarou Hirata, Tokyo (JP); Masaharu Oka, Tokyo (JP); Masahito Sakaki, Tokyo (JP); and Mamoru Saito, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 18/709,045
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Sep. 22, 2022, PCT No. PCT/JP2022/035288 § 371(c)(1), (2) Date May 10, 2024, PCT Pub. No. WO2023/084926, PCT Pub. Date May 19, 2023.
Claims priority of application No. 2021-185120 (JP), filed on Nov. 12, 2021.
Prior Publication US 2024/0425945 A1, Dec. 26, 2024
Int. Cl. C21D 9/46 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/14 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/40 (2006.01)

CPC C21D 9/46 (2013.01) [C21D 8/0226 (2013.01); C21D 8/0242 (2013.01); C21D 8/0273 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/14 (2013.01); C23C 2/0224 (2022.08); C23C 2/06 (2013.01); C23C 2/40 (2013.01); C21D 2211/002 (2013.01); C21D 2211/004 (2013.01); C21D 2211/005 (2013.01)]

4 Claims

1. A hot-rolled steel sheet consisting of, in mass %,

C: 0.040 to 0.120%,

Si: 0.01 to 0.60%,

Mn: 0.50 to 1.50%,

P: 0.025% or less,

S: 0.010% or less,

Al: 0.010 to 0.070%,

N: 0.0070% or less,

Ti: 0.055 to 0.200%,

B: 0.0010 to 0.0050%,

Nb: 0 to 0.20%,

V: 0 to 0.20%,

Cr: 0 to 1.0%, and

Mo: 0 to 1.0%,

with the balance being Fe and impurities,

wherein:

in the microstructure, an area fraction of bainitic ferrite is 85% or more,

a dislocation density is 8.0×10¹³to 100.0×10¹³/m²,

an average equivalent circular diameter of Ti carbides in the hot-rolled steel sheet is 10 nm or less, and

an average equivalent circular diameter of grains of the bainitic ferrite is 15 μm or less.